Vacuum-tube base



June 16, 1925. 1,542,366

w-. R. BROUGH VACUUM TUBE BASE Filed Deb. 2. 1920 June 16. 1925.

UNITED STATES,

PATENT OFFICE.

WILLIAM R. BROUGH, OF EAST ORANGE, NEW JERSEY, ASSIGNOB"TO WESTERN 'TRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION- OF NEW YORK.

VACUUM-TUBE BASE.

Application filed December'2, 1920. Serial No. 427,807. I U

To all whom .z'tmywdnce'rn:

Be it known that I, WILLIAM R. BROUGH,

' a citizen of the United States, residingfat East Orange, in the countyof Essex, State of New Jersey, have invented certain new and usefulImprovements in Vacuum-Tube Bases, of .which the followin is a full,clear, concise, and. exact description.

This invention relates to vacuum tubes and more especially to theconstruction of a base therefor.

In the use ofvacuum tubes in high voltage, high frequency circuits, muchdifficulty has been experienced in insulating the lead wires of the gridand anodeselectrodes. Attempts have heretofore been made to preventdischarges from and corona effectsalong these lead wires by surroundingthem with bodies of insulating material carried by the bottom of thebase. These attempts have failed because with currents of high frequencyand at high voltages the heating of the insulating bodies due todielectric hysteresis is so great as to qulckly cause deterioration anddeformation of the insulation resulting in a breakdown thereof andallowing discharges from the lead wires.. 1

It is an object of this invention to provide abase for vacuum tubesusing highvoltages and high frequencies in which the lead wires for theelectrodes of thetube are insulated from each other and in which theheating of the dielectric of thebase is reduced to such an extentthat'no injurious effects result.

This object is accom lished by using as a part of the base a thin disccomposed of material having a low specific dielectric loss as, forexample, phenol fibre or electrosote and providing terminals in the discfor the electrodes of the tube, said terminals being so proportioned andarranged in the disc as to isolate the anode terminal from the rest andto obtain a minimum potential gradient between the terminals themselvesand between the terminals and the shell of the base.

This invention will be better understood b having reference to thefollowing speci vacuum tube is cemented a metallic shell 12, -the freeend of which is turned-in as at 13 and in which is rolled an inwardlyextending flange 14 near the ed 0 13. Arranged between the in-turned ego 13 and the flange 1 1 is the thin disc 15 composed of an insulate ing.material having a very low specific dielectric loss. In this disc areprovided 16 for the anode of the tube, the terminal 17 for the grid andthe terminals 18 for the cathode. These terminals comprisecylindricalmembers having flanges 19 to contact with one side of thedisc to position them in their apertures and collars 20 to contact withthe opposite side of the disc to clamp said members in place. Theseterminals areprovided with small axial holes which are countersunk attheir ends. The lead wires 21 for the anode, 22 for the grid and 23 forthe cathole are threaded through the holes in the terminals 16, 17 and18 respectively and soldered into the outer ends as at 24 and thenflushed off. This arrangement avoids theconcentration of dielectricstresses around the small diameter of the lead wires and confines thestresses to the periphery of the terminals, thereby-avoiding thepossibility of breakdown of the insulation from corona or highdielectric stresses at the surface of the lead wires.

q The terminals 16 and 17 are so arranged in the disc 15 that theelectrical stresses in the disc adjacent the points of nearest approachof the terminals to the shelland adjacent the'point of nearest approachof the terminal 16 to the terminal 17 are all approximately equal. Theterminals 18 are so apertures in which arelocated the terminal locatedin the base relative to the terminals terminals 18. are equal to eachother and to. the aforementioned stresses. Furthermore,

the diameter of the terminals 16,17 -and18 approximately the smallestpossible consistreducing mechanical stren h.

This effect is accomplis ed' in a 2 50 watt tube, by making the disc ofelectrosote is so adjusted that these equal streses are ent'with thediameter of the disc. The: disc is made as thin as posible'withoutmnduly.

about 3 3/10" diameter and ap roximately. 5/32 thick and making the eective diameter of the terminals approximately 1/2". These. terminals Iare then so arranged that16 and 17 lie on a diameter of the disc and areabout 1 1/16" apart, the terminal 16 being about 7/ and the terminal 17,5/16" from the periphery of the disc. The terminals 18 are approximately1 from the terminal 16 and approximately 19/32" from 17.

Vacuum tubes equipped with this type of base may be operated forindefinite periods in circuits in which the eak voltages of the anodeand grid at comp ete modulation are minimum the dielectric stresses inthe disc adjacent the points of nearest approach of the high tensionterminals to the low potential terminals and because the large surfaceof the disc for the volume thereof allows a considerable heatdissipation therefrom.

' While it is preferable to utilize the described arrangement of theterminals in combination with a thin'insulating disc, it is to beunderstood that they may be arranged as described irrespective of theparticular means used for supporting them in the base.

What is claimed is:

1. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a disc mounted therein, said disc being of insulatingmaterial having a low specific dielectric loss, terminals for theelectrodes of the tube mounted in said disc, each of said terminalsbeing arranged at one vertex of congruent scalene triangles to establishfor the operating voltages of the grid and anode an approximate minimumpotential gradient between the terminal-s for the grid and cathode,between said terminals and the shell and between said terminals and theterminals of the cathode.

2. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a thin disc mounted therein, said disc being composedof insulating material having low specific dielectric loss, terminalsfor the electrodes of the tube mounted in said base, said terminalsbeing arranged 'at the vertices of congruent-scalene triangles theelectrical stresses in'the disc adjacent the 'points of nearest approachof the anode terminal to the grid terminal, the cathode terminals andthe shell, and the electrical stresses in the disc adjacent-the pdintsof nearest approach of the grid terminal to'the cathode terminals andthe shell established therein at the operating voltages of said .grid

and anode are reduced to a minimum.

3. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a thin disc mounted therein, said disc being composedof insulating material having a low specific dielectric loss, terminalsmounted in said base for the electrodes of .said tube, the anode andgrid terminals being arran ed on a diameter of the disc, the distancebetween said grid and anode terminals being approximately 1/3 thediameter of the disc, and the distance between the shell and the anodeterminal bein approximatel 2/5 of said diameter, the cat ode terminalseing arranged in the same half-disc with the grid terminal atpointsequally distant from said grid terminal and also equally distant fromand from the shell a distance approximately 2/5 of said diameter.

5. A base for a vacuum tube having electrodes, said base including asheet metal shell, a thin disc mounted therein, said disc being composedof insulating material having a low specific dielectric loss, terminalsfor the electrodes of the tube mounted in said base, said terminalsbeing arranged in the disc with the anode terminal in a differenthalf-disc from the grid and cathode terminals, said cathode terminalsbeing equally spaced from said grid terminal and also being equallyspaced from said anode terminal.

6. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a thin disc mounted therein, said disc being composedof insulating material having a low specific dielectric loss, terminalsfor the electrodes of the tube mountedin.

said base, said terminals being arranged in the disc with the cathodeand grid terminals grouped in one half of the disc and said anodeterminal in the other half, said grid and anode terminals being on adiameter of the disc and said cathode terminals being equally spacedfrom said grid terminal and also from said anode terminal.

7. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a th1n dlse mounted therein, said disc being composedof insulating material hav ing a low specific dielectric loss, terminalsfor the electrodes of the tube mounted in said base, said terminalsbeing arranged in the disc with the grid and anode terminals on adiameter of the disc at different sides of and at different distancesfrom the center of'the disc. and the cathode terminals being located ona chord of the disc at right angles tosaid diameter and lying betweenthe center of the disc and said grid terminal, said cathode terminalsbeing equally spaced -for the electrodes of'the tube mounted in saidbase, said terminals being symmetrical with respect to one diameteronly, whereby the anode terminal is isolated from the others toestablishlat operating voltages a minimum potential gradient between theanode and the other terminals and between the anode and the shell.

9. A base for a vacuum tube having electrodes, said base comprising asheet metal shell, a thin disc mounted therein, said disc being composedof insulating material having a low specific dielectric loss,'terminalsfor the electrodes of the tube inounted in said base,

each of said terminals being arranged in the disc at an apex oi ascalene trlangle, the anode terminal being isolated from the otherswhereby at operating voltages the electrical stresses in the discadjacent the points of nearest approach of the anode electrode to theshell and to the other terminals are equal.

10. A base for a vacuum tube having electrodes, said base comprisin asheet metal shell, a thin disc mounted. t erein said disc being composedof insulating material having a low specific dielectric loss, terminalsfor the electrodes of the tube mounted in 7 said base, said terminalsbeing arranged in the disc at the corners of a quadrilateral symmetricalwith respect to one of its diagonals, said diagonal being coincidentwith the diameter of the disc, two of said terminals being at differentdistances from said shell. N

diameter of said disc being approirimately twenty times the thickness ofsaid dlsc."

13. A base for a vacuum tube having electrodes, said base comprislng acup shaped member, terminals for the electrodes of the tube mounted insaid member, each of said terminals being arranged at an apex of one oftwo scalene triangles having a common leg, to establish atthe operatingvoltages an approximate minimum potential gradient between the terminalsfor the grid and anode, between said terminals and the wall of saidmember and between said terminals and the terminals of the cathode.

14. A base for. a. vacuum tube havlng an anode, a cathode. and a gridelectrode, said 1 base comprising -a cup shaped member, terminals forthe electrodes of the tube mounted in said member, each of sa 1dterminals being arranged at the vertices of congruent scalene triangleswhereby the electrical stresses in the member adjacent the point ofnearest approach of the anode terminal to the grid terminal, the cathodeterminals and the wall of said member and the electrical stresses inthebase adjacent the points'of nearest approach of the grid terminal tothe cathode terminals and said wall established therein at the operatingvoltages of said vacuum tube are reduced to an ap roximate minimum.

15. A base for a vacuum tube having'an anode, a cathode and a gridelectrode, said base comprising a member having a circular bottom,terminals for the electrodes of the tube mounted in said bottom, theanode ter- Iminal being spaced from each of the other terminals adistance at least equal to 1/3 of the diameter of the base and from thewall of the base a distance approximately 2/5 of thediameter.

16. A base for a vacuum tube containinga cathode, an anode and a controlelectrode, said base comprising a metallic shell, .terminals for saidelectrodes associated with said shell, the terminals for said cathodeand control electrodes being spaced apart a dis tance substantiallythesame as the distance from the terminal of said anode to said shell,said cathode terminals being at a less distance from said shell thansaid control electrode terminal.

17 A base for a vacuum tube containing a cathode, an anode and a controlelectrode, said base comprising a metallic shell, terminals for saidelectrodes associated with said shell, the terminals for said cathodeand control electrodes being spaced apart a distance substantially thesame as the distance from the terminal of said anode to said shell, saidlast mentioned terminal being approximately twice as far from said shellas said other terminals.

18. A base for a vacuum tube having an anode, a cathode and a gridelectrode, said base comprising a member having a circular bottom,terminals for the electrodes of the tube mounted in said bottom, theanode terminal being spaced from each of the other terminals a distanceat least equal to 1/3 of the diameter of the base and from the wall ofthe base a distance approximately 2/5 of the diameter, said otherterminals being spaced apart a distance approximately 2/5 of thediameter.

19. A base for a vacuum tube containing a cathode, an anode and acontrol electrode,

said base comprising a shell, terminals forsaid electrodes associatedwith said shell, I

said cathode terminals being symmetrically arranged with respect to theanode and control electrode terminals, each of the cathode terminalsbeing spaced from the controlelectrode terminal a distance approximatelyequal to the distance between the anode terminal and the shell, and saidanode terminal being spaced from the shell a greater distance than isany of the remaining terminals.

20. A base for a vacuum tube containing a cathode, an anode and a gridelectrode, said base comprising a shell, terminals for said electrodesassociated with said shell, said cathode terminals being symmetricallyarranged with respect to the anode and grid terminals,' said gridterminal being at a greater distance from said' anode terminal than arethe cathodeterminals, each of said cathode terminals being spaced fromthe grid terminal a distance less than the distance between the anodeterminal'and the shell, said anode terminal being spaced from the shella greater distance than is said grid terminal and said grid terminalbeing spaced a greater distance from said shell than are said cathodeterminals.

21. A base for a vacuum tube having elecother terminals a distance atleast equal to 1/3 of the diameter of the base and from the wall of thebase a distance approximate ly 2/5 of the diameter.

22. A base for a vacuum tube having electrodes comprising a memberhaving a circular bottom, terminals for the electrodes of the tubemounted'in said bottom, one of said terminals being'spaced from each ofthe other terminals a distance equal to 1/3 of the diameter of the baseand from the wall of thebase a distance approximatel 2/5 of thediameter, said other termina s being spaced apart a distanceapproximately 2/5 of the diameter.

In witness whereof, I hereunto subscribe my name this 23rd day ofNovember A. D., 1920.

WHJLIAM R. BROUGH.

